( Two studies by researchers at the Unive...)Studies reveal how plague disables immune system, and how to exploit the process to make a vaccine

Both papers -- one published online July 28 in Science Express and one in the August issue of Infection and Immunity -- focus on aspects of the type-III pathway, a molecular syringe that Yersinia pestis, the bacterium that may have killed more people throughout history than any other infectious disease, uses to disable its host's immune system.

"Yersinia pestis is the nastiest thing alive," said study author Olaf Schneewind, M.D., Ph.D., professor and chairman of microbiology at the University of Chicago and director of the Great Lakes Regional Center of Excellence in Biodefense and Emerging Infectious Diseases Research (GLRCE). "It's the most virulent bacterial organism known to mankind. But we now know a little more about how it exercises those powers and we think we can use that knowledge to prepare a preemptive strike."

Historically, the terms "plague" or "Black Death" have referred to the bubonic plague, caused by Yersinia pestis and spread by the bites of infected fleas, which acquire the germ from infected rodents. In the mid-14th century, the plague swept through Europe killing nearly one-third of the population. It returned with a slightly reduced death count about once a generation for centuries.

Although far less common now, the plague has not entirely gone away. There are fewer than 2,000 cases a year worldwide, including 10 to 20 each year in the western United States. One out of seven persons infected dies, even with aggressive treatment.

Since 2001, however, many people have worried that terrorists could exploit Y. pestis as a weapon, spreading it widely and rapidly as an aerosol rather than through fleabites and rodents. Contracted this way -- inf
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Source:University of Chicago Medical Center